1. Field of the Invention
The present invention relates to an encoding device and method, a decoding device and method, and an image information processing system and method. The present invention is preferably applied to an encoding device and a decoding device which abide by, for example, the Joint Photographic Experts Group (JPEG) 2000 standard as well as an image information processing system which is constituted by the encoding device and the decoding device.
2. Description of the Related Art
In recent years, a compression method called a JPEG 2000 standard has been standardized as a new data compression system.
FIG. 1 shows a structure of an encoding device 1 abiding by such a JPEG 2000 standard. Image data D1 to be supplied is subjected to predetermined input image processing such as DC level shift processing and color conversion processing in an input image processing unit 2. Then, obtained signal processing image data D2 is sent to a Discrete Wavelet Transform (DWT) unit 3.
The DWT unit 3 applies wavelet conversion processing to the signal processing image data D2 to be supplied. More specifically, as shown in FIGS. 2A and 2B, the DWT unit 3 passes the signal processing image data D2 through a filter divided into a low frequency pass filter and a high frequency pass filter to thereby subject an image, which is based upon the signal processing image data D2, to band (sub-band) division to divide the image into a horizontal direction and a vertical direction, for example, as shown in FIGS. 2A and 2B.
Note that FIGS. 2A and 2B show the number of divisions of three levels. In the figure, reference sign ‘LL’ denotes a component on a low frequency side both in the horizontal direction and the vertical direction in the signal processing image data D2; ‘LH’, a component of a low frequency side in the horizontal direction and of a high frequency side in the vertical direction in the signal processing image data D2; ‘HL’, a component of a high frequency side in the horizontal direction and of a low frequency side in the vertical direction in the signal processing image data D2; ‘HH’, a component of a high frequency side both in the horizontal direction and the vertical direction in the signal processing image data D2.
Further, the DWT unit 3 sends a wavelet coefficient obtained by such wavelet conversion processing to a quantization unit 4 as DWT data D3.
The quantization unit 4 sequentially quantizes the DWT data D3 to be supplied, divides an obtained quantization-coefficient into code blocks of a predetermined size, and sends the DWT data D3 to a bit model unit 6 of an Embedded Block Coding with Optimized Truncation (EBCOT) block 5 as code block data D4 by a unit of code block.
The bit model unit 6 changes the code block data D4 to be supplied to a coefficient bit model according to (Coefficient Bit Modeling (CBM) processing while scanning the data for each bit plane. Then, the bit model unit 6 sends respective data D5 and D6 of a symbol and a context obtained in this way to an arithmetic coder unit 7.
The arithmetic coder 7 executes predetermined arithmetic encoding operation processing with the symbol data D5 and the context data D6 to be supplied as inputs to thereby generate an encoding column. The arithmetic coder 7 sends this encoding column as encoded data D7 to a packetize stream generation unit 8.
A packetize stream generation unit 8 packetizes the encoded data D7 to a packet format according to the JPEG 2000 standard.
Consequently, encoded packet data D8 complying with a syntax of the JPEG 2000 standard can be obtained.
On the other hand, FIG. 3 shows a structure of a decoding device 10 abide by the JPEG 2000 standard.
In this decoding device 10, encoded data D11, which is an image information part, is extracted from the coded packet data D10 complying with the syntax of the JPEG 2000 standard generated as described above, and the encoded data D11 is sent to an arithmetic decoding unit 13 of the EBCOT block 12.
The arithmetic decoding unit 13 executes predetermined arithmetic decoding operation processing with encoding data D11 and context data D12, which is given from a bit demodel unit 14 in a later stage, as inputs and sends symbol data D13 obtained in this way to the bit demodel unit 14.
The bit demodel unit 14 changes the symbol data D13 to be supplied to a coefficient bit model according to CBM processing and sends decoded code lock data D14 obtained in this way to an inverse quantization unit 15. In addition, the bit demodel unit 14 sends a contax, which is obtained at this point, to the arithmetic decoding unit 13 as contax data D12.
The inverse quantization unit 15 applies inverse quantization processing to the decoded quantization data D14 to be supplied to obtain a wavelet coefficient and sends this wavelet coefficient to an IDWT unit 16 as decoded DWT data D16.
The IDWT unit 16 applies wavelet inverse converted image data D16 obtained in this way to an input image processing unit 17.
Then, the input image processing unit 17 applies predetermined signal processing to this wavelet inverse converted image data D16. Consequently, image data D17 obtained by decoding the image data D1 (FIG. 1) encoded by the encoding device 1 (FIG. 1) can be obtained.
Note that, as a prior art document concerning an encoding device and a decoding device abiding by the JPEG 2000 standard, there is Japanese Patent Laid-Open No. 2002-159009.
However, there is a problem in that encoding processing and decoding processing according to such a JPEG 2000 standard are complicated in contents of the processing, and speedup of the processing is hardly realized.